In one of conventional apparatus for accessing a memory, a memory is accessed in accordance with a physical address comprising more than sixteen bits by the control of a sixteen bit CPU. Consequently, a memory of a capacity which can not be normally accessed in accordance with an address signal of sixteen bits, for instance, a memory of 2M bits is possible to be accessed in accordance with the sixteen bit address signal under program control.
According to the conventional apparatus for accessing of a memory, however, a memory of a capacity larger than a capacity which is accessed in accordance with an address signal composed of a predetermined number of bits must be accessed by the control of a predetermined program. For the reason, there is a disadvantage that a structure of a program becomes complicated to enable memory access outside a block defined by the address signal.